The invention relates to a mobile telecommunication system having an auxiliary routing arrangement.
Known mobile telecommunication systems most frequently comprise a number of mobile telephone switches which are connected to one or a number of base stations that have a number of mobile telephone units associated therewith. Each base station is allocated a number of radio frequencies and preferably has a separate radio channel unit for each of the allocated frequencies, each one of the radio channel units being thereby adapted to operate a different frequency.
With mobile telecommunication systems operating in an area with a high traffic capacity, the respective base station utilises a maximum number of radio channel units and the number of radio frequencies allocated to the base station corresponds to the number of radio channel units.
It is known in a mobile telecommunication system to have an auxiliary routing arrangement between a base station and a mobile telephone unit. In such systems, the base station includes elements that can function as an auxiliary route for a faulty radio channel unit.
It is characteristic of the known mobile telecommunication systems that the auxiliary routes are allocated their own radio frequency and that the radio frequency of the faulty radio channel unit which is not handling traffic, remains blocked until the faulty radio channel unit is repaired and is put into operation again.
Mobile telecommunication systems are also known in which an essentially unchanged traffic-handling capacity is retained, when faults occur in any one or more of the radio channel units of a base station, by having a number of radio channels of the base station on stand-by i.e. set aside for use as and when required. With such an arrangement, the stand-by radio channels are intended for use as spare radio channel units that have to be manually connected into the system by service engineering personnel when one or a more of the radio channel units of the base station have ceased to handle traffic.
With present day telecommunication transmission in mobile systems, there is a great need to be able to utilise the frequency band, which is a limited natural resource, as effectively as possible whilst at the same time being able to retain good preparedness for faults which can occur in part-components, such as the radio channel units, that form part of the mobile telecommunication system. It is, therefore, essential that resources in which faults have occurred and been corrected should be brought back into service as quickly as possible and that faulty part-components, such as radio channel units, are replaced in such a manner that the on-going traffic is disturbed as little as possible. There is also a need for these functions to be effected in an automatic manner, for example, by means of the mobile telephone switch, and not, as is the case with known systems, by the use of manual resources.
There is also a need in mobile telecommunication systems of this category to ensure that the proportion of the radio frequencies allocated to the system which can be actively worked, is as large as possible and is preferably the majority of the radio frequencies.
Furthermore, there is also a need to have an auxiliary routing arrangement for the mobile telecommunication system in order to ensure that the traffic handling capacity of the system remains unchanged when one or more of the radio channel units of the system become faulty and/or cease to handle an adequate level of traffic.
With remotely located base stations in which the number of actively worked radio channel units is not very large, there is also a need to be able to replace a radio channel unit which ceases to handle traffic, with a new functioning radio channel unit without having to send service engineering personnel to the remote location as soon as a fault occurs. The most cost effective way of achieving this is to delay the visit of the service engineering personnel to the remote location until a number of fault reports have been collected.
It is also essential to ensure that, on replacing a faulty radio channel unit which is not handling traffic, the transmitter function of the faulty radio channel unit is switched off in a suitable way and that a fault message is sent to a central operator station or central service station so that suitable measures can be taken to correct the fault and bring the faulty radio channel unit back into service as quickly as possible.
It is an object of the present invention to overcome the problems of known systems and to satisfy the foregoing needs by the provision of a mobile telecommunication system wherein the or each base station has an auxiliary routing arrangement that is adapted to retain an essentially unchanged traffic handling capacity for the telecommunication system even in situations in which one or more radio channel units cease to handle traffic, and become faulty, and wherein the auxiliary routing arrangement is adapted for operation at any of the frequencies which are allocated to the respective base station in the system. The mobile telecommunication system according to the present invention can therefore maintain a high preparedness for the occurrence of one or more faulty radio channel units which are not handling traffic, but can still operate with the majority of the frequencies allocated to the respective base station.